The Kindle depends on the charger to limit output current? No internal current limiting??
What an interesting design choice.

No.
The battery management has a programmable current limiter.
The firmware (at least that of the diagnostic routine) tests for:
off, 100ma, 500ma, other
And the author assumed "other" would be between off ... 500ma.

The diagnostic routine (with the battery charge level at 30%) was reporting a charge current of 800ma (the maximum the charger could output).
And at that point, I didn't realize the hardware could not handle that - I could have just pulled the plug and saved my Kindle.

Eventually, Amazon will get back all Kindles that shipped with that firmware error and an Amazon wall charger.
At least the author of that routine put his name on it - they know who's paycheck to deduct for the self-destructing Kindles.